Teens who had low sleep efficiency in objective testing showed markedly increased rates of prehypertension -- defined as the top 10% of blood pressure levels for age, sex, and height -- with an adjusted odds ratio of 3.5 (95% CI 1.5 to 8.0), reported Susan Redline, M.D., M.P.H., of Case Western Reserve University, and colleagues online in Circulation.

Sleep duration of 6.5 hours or less was also associated with increased rates of prehypertension, but barely missed statistical significance (adjusted OR 2.5, 95% CI 0.9 to 6.9), the researchers said.

"Our data underscore the need to monitor the quantity and quality of sleep as part of health supervision in children," the researchers wrote.

In an interview, Dr. Redline said poor sleep is common among adolescents, in no small measure because of "the invasion of electronic devices into the bedroom."

With televisions, computers, stereos, iPods, and cell phones now standard equipment for many teenagers, using them often comes at the expense of sleep, she said.

Consequently, she said, physicians should routinely question their adolescent patients and their parents about sleep habits. She said teenagers should be getting at least nine hours of sleep each night.

In the study, involving a sample of 238 generally healthy adolescents ages 13 to 16, barely 20% of teens got as much as 8.5 hours. The mean was 7.71 hours (SD 1.03).

Sleep efficiency was measured with wrist-mounted actigraphy monitors over five to seven days and defined as the time asleep divided by total time in bed.

Participants also underwent polysomnography in a sleep lab, which generally confirmed the actigraphy findings.

The researchers found that 25.6% of the sample had sleep efficiency of 85% or less, which they used as a cutoff for poor sleep quality.

Prehypertension was seen in 19 participants and another 14 had overt hypertension, defined as systolic or diastolic hypertension in the 95th percentile.

They found that 54.6% of those with abnormally high blood pressure had low sleep efficiency, compared with 21.0% of normotensive participants (P<0.0001).

Similarly, 21.1% of prehypertensive teens got no more than 6.5 hours of sleep per night, versus 8.8% of those with normal blood pressure (P=0.059).

The odds ratio for prehypertension among teens with poor versus normal sleep efficiency, before adjustments, was 4.5 (95% CI 2.1 to 9.7).

The odds ratio fell back to 3.5 after controlling for sex, body mass index, and socioeconomic status. Male gender, high BMI, and lower middle-class status contributed to poor sleep efficiency.

Mean systolic and diastolic pressures among those with sleep efficiency of 85% or less were 118.4 (SD 9.9) and 67.4 (SD 7.4) mm Hg, respectively.

Earlier studies had shown that poor sleep quality is associated with obesity and impaired glucose tolerance in pediatric patients, but the new study is the first to demonstrate an association with hypertension in this population, the researchers said.

Dr. Redline said the study could not definitively show that poor sleep causes high blood pressure, but current knowledge of the relationship between sleep and metabolism suggests such a relationship is likely.

She said there was essentially no reason to suspect the reverse, that blood pressure abnormalities by themselves would cause sleep problems.

The researchers also found no contribution to the sleep quality-blood pressure link from such factors as asthma, attention deficit disorder, or caffeine or tobacco use.

Dr. Redline emphasized that while the researchers used a 6.5-hour cutoff to define short sleep duration for purposes of the study, it should not be taken as the minimum for normal, healthy sleep in the real world.

The study was funded by the National Institutes of Health. Co-authors reported relationships with Advanced Brain Monitoring Inc. and Cleveland Medical Devices Inc.

Reviewed by Zalman S. Agus, MD Emeritus Professor University of Pennsylvania School of Medicine

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